Issue # 5, July 5, 2000

• Trying to Fight the Onslaught of Mosquitoes

• Smallgrain Fungicide Rainfastness

• EPA Extends Exemption for Raptor on Dry Beans

• Rain Increases Canola Stem Rot Potential

• High Potential For White Mold in Dry Beans

• Bacterial Disease Found in HRSW

Trying to Fight the Onslaught of Mosquitoes

    Mosquitoes are causing outdoor activities to be unbearable. The mosquitoes that are buzzing about are the flood water type. Their eggs have been laid in damp soil near areas that pond on a regular basis. When water is present, the larvae hatch from the eggs. It will take about 14 days for larvae to emerge as adults. Many attempts to manage mosquitoes focus on controlling the larvae. This is the time when they are confined and most concentrated. However, with the saturated soils and most recent rains, there can be numerous breeding sites around, and difficult to treat them all adequately. Where standing water is a problem around the home or farmstead, one of the recommended treatment programs is the use of Bacillus thuringiensis var. israelensis (sold as Mosquito Dunks , Bactimos , Teknar , and Vectobac ). Mosquito Dunks , packaged as briquets, are slow release (working for about 30 days). Also, they remain effective even with the alternate wetting and drying that occurs in these ponding sites. Local availability of the products may be the challenge. Controlling adult mosquitoes is a big task because of their mobility. Generally, the larger the area treated, the more successful the control. Even then, the results are temporary, as new adults migrate into the area or emerge from breeding sites. Around the home, control is most practical for short term reductions of mosquitoes, such as for a summer picnic. In those cases, treat 12 to 24 hours prior to the event. This insures the spray has dried on vegetation before people are present. It will also reduce the mosquito population before the guests arrive.
    For most homeowners, sprays containing malathion, permethrin, or carbaryl (Sevin ) should be directed at vegetation where mosquitoes rest during the day. Treat at dusk or early in the morning. Around a farmstead, there is one other option. Farmers who use Tempo to treat grain bins will discover, when they read the label, that this product is approved for use to treat landscape areas (shrubs and tall grass) for the control of several nuisance pests, including mosquitoes. This product should be used only by licensed applicators. It is NOT approved for application to edible crops in the garden.
    Finally, the best protection from mosquitoes is still the use of personal repellants containing DEET. Protection lasts from 1 to 5 hours. Follow these general guidelines for their use:

• Read all directions before using this product;
• Do not spray in enclosed areas;
• Do not apply over cuts, wounds, or irritated skin;
• Do not apply to eyes and mouth;
• Do not apply to the hands of young children;
• On children, use a product containing less than
• 20% DEET. Do not spray directly over the face;
• Avoid breathing DEET aerosol;
• Do not use near food.
• Use just enough repellent to cover exposed skin and clothing.  Do not use under clothing.  Reapply as necessary, but avoid overexposure.

Submitted by: Phillip Glogoza, NDSU Extension Entomologist

Rainfall following a fungicide application in wheat or barley is certainly likely given our recent wet cycle. Protectant fungicides (e.g. mancozeb) are readily washed off the treated crop if a substantial rain occurs within 8 hours of application. Retreating the field may be required for maximum protection.
    Eighty percent of locally-systemic fungicides (e.g. Folicur, Tilt, and Benlate) are absorbed by the plant within the first hour after application. The remaining fungicide is absorbed in time and the optimum rainfastness is reached at 4 hours after application. Retreating the field is not needed if it rains 1.5 to 2 hours after applying these fungicides.

EPA Extends Exemption on Raptor for Dry Beans

The EPA has approved a ND request to extend the exemption on Raptor from June 30 to July 15 due to adverse weather conditions which has prevented many producers from applying Raptor during the original exemption period that ended June 30.  The exemption now allows a single ground or aerial application of Raptor at a rate of 4 ounces of product per acre through July 15, 2000. Applicators must follow all instructions, warnings and precautions on the product label and have a copy of the exemption label in their possession during application.

Rain Increases Canola Stem Rot Potential

    Recent heavy rains in North Dakota and northwestern Minnesota will increase the potential of Sclerotinia stem rot in canola fields where soils have been saturated for 10 days before flowering, says Art Lamey, extension plant pathologist at North Dakota State University.  Lamey says the Sclerotinia spore producing bodies have been observed at various locations from central Minnesota to north central North Dakota. Several petal tests, which measure infection potential, have also been positive in these areas.  Canola growers could consider applying a fungicide if the crop has good yield potential, it is growing in an area that has had Sclerotinia in recent years, and if the soils have been wet, says Lamey. Timing is critical for spraying, he says. Quadris should be applied when the crop is at 10 to 25 percent bloom; Ronilan should be applied at 20 to 25 percent bloom.  Several early fields are beyond this stage, so these fields might not pay for the treatment.  If your fields are in the right stage, with the sunflower head rot last year, those fields should pay for the treatment.

High Potential for White Mold in Dry Beans

    The saturated conditions along with the high amounts of sclerotia bodies from sunflower head rot in 1999, make for ideal conditions for white mold in dry beans.  Start monitoring fields soon to watch for budding and the beginning of flowering.  Two fungicides are labeled for control in dry beans.  
    Benlate 50% (benomyl), is recommended to be applied at 1.5 - 2 lb/A at 10 to 20% bloom if one application is to be used.  If two applications are to be used, apply the first application at early bloom and the second application at peak bloom (7-10 days later).  Complete coverage is essential for control.  
    Topsin M WSB 70% (thiophanatemethyl), is recommended at 1-1.5 lb/A at 50-70% bloom.  If two applications are to be used, apply the first at early bloom and the second at peak bloom (7-10 days later).  Complete coverage is essential for control.
    Over the last two years, Griggs, Traill and Steele Counties have been conducting treatments with calcium mixed with fungicides.  These treatments were using a 1/2 rate of fungicide and one gallon of liquid calcium.  We did see increases in yields over the checks.  We are conducting this trial again this year and hope to find a combination that will be under $12.00/A treatment.  This should be a good year to see how much affect calcium has on white mold control.  As of this writing the jury is still out.  With the conditions that we have this year, I would strongly urge the use of a fungicide whether it is a reduced rate or the whole rate.

Bacterial Disease Found in HRSW

    Last week, Jonathon Erickson of AgAdvantage, brought in a crop sample of HRSW that had the flag leaf showing disease like symptoms.  The plants were found in various areas of the crop, often associated in a circle like pattern.  I showed the sample to Marcia McMullen, Extension Plant Pathologist, and she said this type of injury has been found over the years in the Casselton area.  These symptoms usually occur following heavy, windy rain storms similar to the storms over the past two weeks.  Symptoms will cause the flag leaf to turn light brown and looks as if spread was caused by water running down the leaf.  There is nothing you can do to prevent this disease.  The good thing is it does not spread unless another event happens that causes it.  It is just one of those unexplainable events of nature.  

Please Contact Our Office For Additional Information
E-mail: griggs@ndsuext.nodak.edu
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